Large machines such as haul trucks, vocational trucks, wheel loaders, motor graders, and other excavation equipment are each provided with a suspension system that distributes and transfers a load of the machine to one or more axles. A common suspension system used in these applications is known as a four-bar linkage system.
A four-bar linkage system comprises four different bars or links that are pinned at their ends to each other so that the links move in parallel planes. In a typical machine application, the frame of the machine can be considered the first link, the axle can be considered the second link, and two parallel links that connect the frame to the axle can he considered the third and fourth links. With this configuration, the axle can be constrained relative to the frame to limit movement along a particular arcuate trajectory. In other words, the axle may be allowed to move in a vertical direction relative to the frame, but may be limited from significant movement in a side-to-side or fore-aft direction of the frame. One or more shock absorbers may he located to cushion the vertical movement.
In some applications, it may be possible for a lateral spacing at ends of the links to be too great. In these situations, the links could tilt out of their associated planes of motion (i.e., fall over) and collide with surrounding geometry (e.g., with portions of the other links or clevises that support the links). This can cause damage to the links (e.g., to bearings inside the ends of the links), thereby reducing a life of the suspension system.
An exemplary suspension system is disclosed in U.S. Pat. No. 7,063,342 that issued to Seki on Jun. 20, 2006 (“the '342 patent”). The suspension system of the '342 patent includes a suspension arm having a through hole formed in one end. A bearing fits centrally in the through hole, and spacer members are inserted into opposing ends of the through hole. One end of the suspension arm is installed into the frame of a vehicle by means of a bolt inserted through the bearing and the spacer members. The spacers may function to position the suspension arm at a desired location.
Although the spacer members of the '342 patent may help to improve longevity of the suspension system, they may lack broad applicability. In particular, the spacer members may require significant time and effort to replace in the field. That is, installation of the spacer members may require disassembly of the bolt, in order for the bolt to pass through the ends of the spacer members. For this reason, it may only he practical to use the spacer members with a new machine, because replacing the spacer members of an existing machine could require that the machine be taken out of service. Extended machine downtime can result in lost productivity and profit.
The disclosed suspension system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.